A hard disk drive magnetically writes and reads data to and from a rotating disk. Hard disk drives are widely used as an auxiliary storage device for a computer system as they can access mass data at a high speed. Access to a hard disk drive can be characterized as a physical mode and a logical mode. The physical mode is utilized when manufacturing the drive in a factory and used to find out a physical error or a defect position during a drive test by sequentially numbering tracks of the drive from an outer diameter to an inner diameter.
The logical mode (hereinafter, referred to as the user mode) is used when the user of a host computer accesses the drive and is used by sequentially numbering the tracks from the outermost track to the innermost track, like the typical physical mode. However, the user mode may be used by selecting an appropriate value according to the capacity of the drive, irrespective of the number of physical heads or the number of tracks. In both the physical mode and the user mode, when sequentially searching the tracks of the drive, the heads are sequentially switched within the same track (i.e., within one cylinder) and then the tracks are searched generally.
A process for sequentially searching and mapping the tracks in the user mode will now be described with reference to FIGS. 1 to 3. FIG. 1 is a block diagram of a general hard disk drive. In the drawing, the hard disk drive of a multiplatter system including two disks 2 and four heads 4 is illustrated. In the hard disk drive using the multiplatter system, disks 2, of a stack form generally, are installed at one spindle motor 30, and each of both surfaces of each disk corresponds to one head. The spindle motor 30 rotates a hub 6 around which the disks 2 are attached.
Head 4 is positioned on the surface of disk 2 and installed at a vertically extended arm 8 of an arm assembly of a rotary voice motor (VCM) 24. Pre-amplifier 12 pre-amplifies a signal picked up by one of heads 4 when data is read, and supplies an analog read signal to a read/write channel circuit 14. When data is written, pre-amplifier 12 drives one of heads 4 so as to write encoded write data supplied from read/write channel circuit 14 on disk 2. In such case, pre-amplifier 12 selects one of heads 4 by the control of a disk data controller (DDC) 32 controlled by a microcontroller 18.
Read/write channel circuit 14 generates read data RDATA by detecting and decoding a data pulse from the read signal received from pre-amplifier 12, and decodes write data WDATA received from disk data controller 32 to be supplied to pre-amplifier 12. Moreover, read/write channel circuit 14 generates a position error signal (PES) by demodulating head position information which is one of servo information written in the disk.
The position error signal PES, generated from read/write channel circuit 14, may be supplied to analog-to-digital (A/D) converter 16. A/D converter 16 converts the position error signal PES to a digital level value corresponding to its level and supplies the digital level value to the microcontroller 18. The DDC 32, controlled by the microcontroller 18, writes data received from host computer on disk 2 through read/write channel circuit 14 and pre-amplifier 12, or reads data from disk 2 to be supplied to the host computer.
DDC 32 also interfaces communication between the host computer and microcontroller 18. Microcontroller 18 controls the DDC 32 in response to a read or write command received from the host computer and controls track search and track follow-up. In this case, microcontroller 18 uses the position error signal PES supplied from A/D converter 16 to control track follow-up. Microcontroller 18 includes a ROM (Read Only Memory) having a control program of the hard disk drive and a flash memory for storing track-0 information.
Digital-to-analog (D/A) converter 20 converts a position control value of heads 4 to an analog signal A VCM driver 22 supplies, to VCM 24, a driving current I(t) for driving an actuator by a signal received from D/A converter 20. VCM 24 shifts heads 4 within the disk in response to the direction and level of the driving current received from VCM driver 22. Motor controller 26 controls spindle motor driver 28 according to a rotating control value of disks 2 generated from microcontroller 18. Spindle motor driver 28 rotates disks 2 by driving spindle motor 30 by control of motor controller 26. The spindle motor 30 rotates the hub 6 and so rotates the disks 2 that are attached to the hub 6.
FIG. 2 is a front view of a head disk assembly (HDA) illustrating a track mapping process of the hard disk drive using the multiplatter system. Each of heads H0 to H3 is fixed to gimbals of an end of a suspension of swing arm 8 and moves horizontally on disk 2 with the center axis of a pivot bearing (not shown).
FIG. 3 is a diagram illustrating a direction of the track mapping process FIG. 2. In FIGS. 2 and 3, it is assumed that platters corresponding to respective heads H0, H1, H2 and H4 are defined as A, B, C and D, and there are n+1(0.about.n) tracks on each platter. Referring to FIGS. 2 and 3, when sequentially searching tracks in the user mode, heads H0, H1, H2 and H3 are moved to the outermost track of the physical track.
Thereafter, all tracks within the same cylinder are searched by sequentially performing head switching. Finally, the next cylinder of the mapping completed cylinder is searched. That is, track mapping is done up to the innermost track. Consequently, the track mapping is implemented in the order of head H0, track A0.fwdarw.head H1, track B0.fwdarw.head H2, track C0.fwdarw.head H3, track D0.fwdarw.head H0, track A1.fwdarw.head H1, track B1.fwdarw.. . . . ..fwdarw.head H1, track Bn.fwdarw.head H2, track Cn.fwdarw.head H3, track Dn. The direction of the track mapping can be briefly expressed as illustrated in FIG. 3. In FIG. 3, a reference symbol CY designates a cylinder.
Generally, in a hard disk drive, time for searching one track is shorter than head switching time. The reason is that since a recording density of TPI (track per inch) of disk 2, that is, of a disk radius direction is very high, the alignment of the head may cause, during servo writing, some transformation by the assembly of a cover or a printed circuit board (PCB). Furthermore, in the typical hard disk drive, since force is applied to the swing arm caused by a push rod during servo writing, alignment of the head may be changed.
Therefore, when carrying out the above-described track mapping for total disk surfaces of a drive, track mapping time is delayed by head switching time, thereby deteriorating the performance of the drive. Further, if the above-described track mapping process is implemented, since a file allocation table (FAT), a route directory, a master boot record, and the like, having position information of a file in a DOS.TM. or Windows.RTM. environment are generally positioned at a user track-0, the tracks from an outer diameter region to an inner diameter region should be searched in the worst case.